WO2016006169A1

WO2016006169A1 - Fuel injection control device for internal combustion engine

Info

Publication number: WO2016006169A1
Application number: PCT/JP2015/003058
Authority: WO
Inventors: 優一竹村; 和田　実; 福田　圭佑
Original assignee: 株式会社デンソー
Priority date: 2014-07-07
Filing date: 2015-06-18
Publication date: 2016-01-14
Also published as: DE112015003142T5; JP2016017435A

Abstract

An engine (10) is provided with a gas fuel injection valve (21) and a starter (25) as electric loads that are driven by power supply from a battery (93). A control unit (80) is provided with a combustion control unit that executes combustion in the engine (10) by supplying power from the battery (93) to the gas fuel injection valve (21) when an engine start request is made. Further, valve opening prompting control is performed for supplying power to the gas fuel injection valve (21) in a period in which the driving of the starter (25) is stopped in a predetermined period from when the engine start request is made until the combustion in the engine (10) is actually started with the power supply to the gas fuel injection valve (21) by the combustion control unit.

Description

Fuel injection control device for internal combustion engine

Cross-reference of related applications

This application is based on Japanese Application No. 2014-139745 filed on July 7, 2014, the contents of which are incorporated herein by reference.

The present disclosure relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for an internal combustion engine including a fuel supply system capable of supplying gaseous fuel to a fuel injection valve.

Patent Document 1 discloses an internal combustion engine that is driven by burning gaseous fuel such as compressed natural gas (CNG). In the internal combustion engine described in Patent Document 1, in view of the fact that the operation of the fuel injection valve for gaseous fuel becomes difficult due to a decrease in the voltage of the on-vehicle power source at low temperatures, the supply to the fuel injection valve It is disclosed that the fuel injection valve is operated during a crank angle period during which the voltage increases or during an expansion stroke of the cylinder.

However, since the power supply voltage is always maintained at a low voltage when the on-vehicle power supply is deteriorated or at an extremely low temperature of, for example, −30 ° C. or lower, the fuel injection valve is driven to open and overlaps with the drive timing of the starter. In such a case, there is a possibility that the fuel injection valve cannot be driven to open due to insufficient driving power.

JP 2010-132950 A

An object of the present disclosure is to provide a fuel injection control device for an internal combustion engine capable of ensuring the startability of the internal combustion engine by improving the operability of the gaseous fuel injection valve.

A fuel injection control device of the present disclosure includes a gas fuel injection valve that injects gaseous fuel as an electric load driven by power supply from a power supply unit, and a start that applies initial rotation to an engine output shaft when a start request occurs The present invention is applied to an internal combustion engine including the device. The fuel injection control device according to the present disclosure includes a combustion control unit that supplies power to the gaseous fuel injection valve from the power supply unit and performs combustion in the internal combustion engine when the start request is generated, and the start request is generated. Within a predetermined period until the combustion in the internal combustion engine actually starts with the supply of electric power to the gaseous fuel injection valve by the combustion control unit. A valve opening control unit that performs valve opening promotion control for supplying electric power to the gaseous fuel injection valve.

When driving the starter to apply initial rotation to the engine output shaft, a relatively large drive power is required. Therefore, when the internal combustion engine is started, when the fuel injection by the gaseous fuel injection valve is attempted to overlap with the driving of the starting device, the gas is supplied due to the shortage of the supplied power even though the electric power is supplied to the gaseous fuel injection valve. There is a concern that the fuel injection valve cannot be opened. In such a case, gaseous fuel cannot be supplied to the internal combustion engine, and the internal combustion engine may not be started. In particular, in the gaseous fuel injection valve, when a sealing member or the like for ensuring airtightness is disposed in the injection hole, the initial opening operation after the start request is difficult, and the above-described concern is likely to occur.

According to the above configuration, electric power is supplied to the gaseous fuel injection valve during a period in which driving of the starter is stopped during a period from when the start request of the internal combustion engine is generated to when combustion in the internal combustion engine is actually started. Supply. According to such a configuration, it is possible to supply power to the gaseous fuel injection valve in a state in which the driving power required for opening the gaseous fuel injection valve is sufficiently secured, and to appropriately open the gaseous fuel injection valve. . Further, once the gaseous fuel injection valve is opened, the subsequent operability is improved. As a result, gaseous fuel can be supplied to the internal combustion engine, and startability of the internal combustion engine can be ensured.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.
FIG. 1 is a configuration diagram showing an outline of an engine fuel injection system. FIG. 2 is a diagram illustrating a configuration of a power supply system for each electric load. FIG. 3 is a time chart showing a specific mode of valve opening promotion control of the first embodiment. FIG. 4 is a flowchart showing a processing procedure for valve opening promotion control according to the first embodiment. FIG. 5 is a time chart showing a specific mode of valve opening promotion control of the second embodiment. FIG. 6 is a flowchart illustrating a processing procedure for valve opening promotion control according to the second embodiment. FIG. 7 is a time chart showing valve opening promotion control of another embodiment. FIG. 8 is a diagram illustrating another example of the energization mode of the valve opening promotion control. FIG. 9 is a flowchart showing a processing procedure for valve opening promotion control according to another embodiment. FIG. 10 is a time chart showing valve opening promotion control of another embodiment. FIG. 11 is a time chart showing valve opening promotion control of another embodiment.

(First embodiment)
Hereinafter, a first embodiment embodying the present disclosure will be described with reference to the drawings. This embodiment is embodied as a fuel injection system for a multi-cylinder engine mounted on a gas-only vehicle that uses compressed natural gas (CNG), which is gaseous fuel, as fuel for engine combustion. An overall schematic diagram of this system is shown in FIG.

1 is an inline three-cylinder spark ignition engine, and an intake system 11 and an exhaust system 12 are connected to an intake port and an exhaust port, respectively. The intake system 11 has an intake manifold 13 and an intake pipe 14. The intake manifold 13 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 13a connected to the intake port of the engine 10, and a collective portion 13b connected to the intake pipe 14 on the upstream side. ing. The intake pipe 14 is provided with a throttle valve 15 as an air amount adjusting unit. The throttle valve 15 is configured as an electronically controlled throttle valve whose opening degree is adjusted by a throttle actuator 15a such as a DC motor. The opening degree (throttle position) of the throttle valve 15 is detected by a throttle position sensor 15b built in the throttle actuator 15a. The intake port of the engine 10 is provided with an intake valve, and an air-fuel mixture is introduced into the cylinder 24 by opening the intake valve.

The exhaust system 12 has an exhaust manifold 16 and an exhaust pipe 17. The exhaust manifold 16 has a plurality of (for the number of cylinders of the engine 10) branch pipe portions 16a connected to the exhaust port of the engine 10 and a collecting portion 16b connected to the exhaust pipe 17 on the downstream side. ing. The exhaust port of the engine 10 is provided with an exhaust valve. Exhaust gas after combustion of the engine 10 is discharged from the cylinders 24 of the engine 10 to the exhaust pipe 17 by opening the exhaust valve. The exhaust pipe 17 is provided with an exhaust sensor for detecting exhaust components and a catalyst 19 for purifying the exhaust. As the exhaust sensor, an air-fuel ratio sensor 18 that detects the air-fuel ratio from the oxygen concentration in the exhaust is provided.

A spark plug 20 is provided in each cylinder 24 of the engine 10. A high voltage is applied to the ignition plug 20 at a desired ignition timing through an ignition device 20a including an ignition coil. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 20, and the fuel introduced into the combustion chamber of each cylinder 24 is ignited and used for combustion.

The present system has a gaseous fuel injection valve 21 as a fuel injection unit that injects and supplies gaseous fuel (CNG fuel) to the engine 10. The gaseous fuel injection valve 21 is a port injection type that injects fuel into the branch pipe portion 13 a of the intake manifold 13.

The gaseous fuel injection valve 21 is an open / close type control valve in which a valve body is lifted from a closed position to an open position by electrically driving an electromagnetic drive unit, and is an on / off type input from the control unit 80. Is opened by the valve opening drive signal. This gaseous fuel injection valve 21 has a self-seal (self-sealing) structure in which a closing sealing property is imparted by the pressure (supply gas pressure) of the gaseous fuel supplied to itself. Specifically, when the gaseous fuel injection valve 21 is in the closed state, the supply gas pressure (corresponding to the injection pressure) acts on the valve body to set the valve body to the valve closing position. When the electromagnetic drive unit is energized, the valve body overcomes the force in the valve closing direction and is displaced in the valve opening direction, thereby opening the injection hole. In addition, a rubber seal member, for example, is disposed in the injection hole of the gaseous fuel injection valve 21, thereby ensuring a closing sealing property when the valve is closed.

Next, the gaseous fuel supply unit 40 constituting the fuel supply system of the engine 10 will be described. In the gaseous fuel supply unit 40, the gaseous fuel injection valve 21 is connected to a gas tank 42 via a gas pipe 41. In the middle of the gas pipe 41, a regulator 43 having a pressure adjustment function for adjusting the pressure of the gaseous fuel supplied to the gaseous fuel injection valve 21 is provided. The regulator 43 adjusts the pressure of the gaseous fuel stored in the gas tank 42 in a high pressure state (for example, a maximum of 20 MPa) so as to become a predetermined set pressure Po (for example, about 0.3 to 0.4 MPa). The gaseous fuel after the decompression adjustment is supplied to the gaseous fuel injection valve 21 through the gas pipe 41.

The gas pipe 41 further includes a tank main stop valve 44 disposed near the fuel outlet of the gas tank 42, and a shut-off valve disposed downstream of the tank main stop valve 44 and near the fuel inlet of the regulator 43. 45 is provided. These

valves

44 and 45 allow and block the flow of gaseous fuel in the gas pipe 41. Both the tank main stop valve 44 and the shut-off valve 45 are electromagnetic on-off valves, and are normally closed types in which the flow of gaseous fuel is blocked when not energized and the flow of gaseous fuel is allowed when energized. In the gas pipe 41, pressure sensors 46a and 46b for detecting the fuel pressure and

temperature sensors

47a and 47b for detecting the fuel temperature are provided on the upstream side and the downstream side of the regulator 43, respectively. A supply gas pressure (injection pressure) to the gaseous fuel injection valve 21 is detected by a pressure sensor 46 b provided on the downstream side of the regulator 43.

In addition, this system is provided with a starter 25 as a starting device that applies initial rotation to the output shaft (crankshaft) of the engine 10 when the engine is started. The starter 25 of the present embodiment is driven by being supplied with electric power from the in-vehicle battery by switching the power supply state and the power cut-off state by a switch operation (for example, key operation) of the driver. The cranking of the engine 10 is performed by this driving.

The control unit 80 includes a CPU 81, a ROM 82, a RAM 83, a backup RAM 84, an interface 85, and a bidirectional bus 86. The CPU 81, ROM 82, RAM 83, backup RAM 84, and interface 85 are connected to each other by a bidirectional bus 86.

The CPU 81 executes a routine (program) for controlling the operation of each unit in the system. The ROM 82 stores in advance various data such as a routine executed by the CPU 81, maps (including tables, relational expressions, etc. in addition to maps) and parameters referred to when the routine is executed. The RAM 83 temporarily stores data as necessary when the CPU 81 executes a routine. The backup RAM 84 appropriately stores data under the control of the CPU 81 in a state where the power is turned on, and retains the stored data even after the power is shut off.

The interface 85 includes the throttle opening sensor 15b, the air-fuel ratio sensor 18, the pressure sensors 46a and 46b, the

temperature sensors

47a and 47b, and other sensors (crank angle sensor, cam angle sensor, air flow sensor) provided in this system. Meter, cooling water temperature sensor, battery voltage detection sensor, etc.), and outputs (detection signals) from these sensors to the CPU 81. The interface 85 is electrically connected to drive units such as the throttle actuator 15a, the ignition device 20a, the gaseous fuel injection valve 21, the tank main stop valve 44, the shut-off valve 45, and the like, and receives the drive signal sent from the CPU 81. These drive units are driven by outputting them toward the drive unit. That is, the control unit 80 acquires the operating state of the engine 10 based on the output signals of the above-described sensors, and implements the above-described driving unit control based on the acquired operating state.

Various electric loads such as the gaseous fuel injection valve 21, the ignition device 20 a, the starter 25, the tank main stop valve 44, and the shut-off valve 45 described above operate by receiving power supplied from the on-vehicle battery. The configuration of the power supply system is shown in FIG. In FIG. 2, the gaseous fuel injection valve 21, the ignition device 20 a, the tank main stop valve 44, the shutoff valve 45, and the starter 25 of each cylinder as an electric load are connected to a battery 93 as a power supply unit via a power supply line 92. ing. Each of these electric loads is driven by power supply from the battery 93. A starter switch 27 is provided in the power supply path connecting the starter 25 and the battery 93, and the starter switch 27 can be switched on / off by the operation of the driver.

Control signals from the control unit 80 are input to the gaseous fuel injection valve 21, the ignition device 20a, the tank main stop valve 44, and the shutoff valve 45. For example, the gaseous fuel injection valve 21 is opened according to a control signal (valve opening drive signal) from the control unit 80 to inject gaseous fuel. The ignition device 20a outputs a high voltage in accordance with a control signal from the control unit 80, and causes an ignition spark in the ignition plug. The tank main stop valve 44 and the shutoff valve 45 are switched from the closed state to the open state in response to a control signal from the control unit 80. In addition, an ON / OFF switching signal of an ignition switch (IG switch 26) as a start switch of the engine 10 operated by a driver is input to the control unit 80.

Since the starter 25 requires a relatively large driving power, when the fuel injection of the gaseous fuel injection valve 21 is performed overlapping the driving timing of the starter 25, the electric power for driving the gaseous fuel injection valve 21 to open is required. It is thought that it is insufficient. In particular, when the supply gas pressure of the gaseous fuel injection valve 21 is in a high pressure state when the engine 10 is started, or when the battery voltage when the gaseous fuel injection valve 21 is driven to open is low, the gaseous fuel injection is performed. It becomes difficult to open the valve 21.

Specifically, when the gaseous fuel injection valve 21 is closed, a force in the valve closing direction acts on the valve body by the supply gas pressure. Therefore, when the gaseous fuel injection valve 21 is opened, it is necessary to generate a driving force that overcomes the force in the valve closing direction. At this time, if the supply gas pressure of the gaseous fuel injection valve 21 is in a high pressure state, a relatively large drive power is required to displace the valve body in the valve opening direction. Therefore, when fuel injection by the gaseous fuel injection valve 21 is performed overlapping with the drive timing of the starter 25, power for driving the gaseous fuel injection valve 21 to open is insufficient, and as a result, fuel injection is not performed. There is concern.

Also, for example, when the battery 93 is deteriorated at an extremely low temperature of −30 ° C. or lower, the voltage level of the battery 93 is always lowered. Therefore, when the gaseous fuel injection valve 21 is driven to open at the same time as the starter 25 is driven, the gaseous fuel injection valve 21 is driven to open because the battery voltage is in a low pressure state. It is conceivable that sufficient electric power cannot be supplied to the gaseous fuel injection valve 21. In particular, in the gaseous fuel injection valve 21, a seal member is generally attached to the injection hole in order to prevent fuel leakage, and when the engine is started, the injection hole is difficult to open due to sticking of the seal member.

In addition, the following is mentioned as a factor in which the supply gas pressure of the gaseous fuel injection valve 21 becomes a high pressure state at the time of engine starting. That is, with the opening of the tank main stop valve 44 and the shutoff valve 45, the flow of gaseous fuel to the injection valve side is allowed. At this time, immediately after the tank main stop valve 44 and the shutoff valve 45 are opened, a transient pressure regulation delay of the regulator 43 occurs, and the supply gas pressure may become a high pressure state due to this pressure regulation delay. Such a pressure regulation delay of the regulator 43 is particularly likely to occur during a cold start where a response delay of the valve body of the regulator 43 is more likely to occur.

Therefore, in the present embodiment, the drive of the starter 25 is stopped during the period from when a request for starting the engine 10 is generated to when combustion in the engine 10 is actually started with the supply of power to the gaseous fuel injection valve 21. Electric power is supplied to the gaseous fuel injection valve 21 during this period. Thereby, the control (valve opening promotion control) for promoting the opening of the gaseous fuel injection valve 21 is performed. In particular, in the present embodiment, when it is detected that the gas fuel injection valve 21 has not been opened despite the power supply to the gas fuel injection valve 21 in response to the engine start request, the engine combustion is actually performed thereafter. The electric power is supplied to the gaseous fuel injection valve 21 while the starter drive is stopped during the period until the start.

That is, if the engine 10 is not started even when the IG switch 26 and the starter switch 27 are turned on, the driver normally performs an operation of turning off the starter switch 27 and then turning on the starter switch 27 again. Try to start. In this embodiment, in the series of operations of such a driver, after the starter switch 27 is once turned off, the drive of the starter 25 is stopped in a period until the starter switch 27 is turned on again. Focusing on the fact that the battery voltage is sufficiently secured, power is supplied during this period to open the gaseous fuel injection valve 21 once.

Next, the valve opening promotion control of this embodiment will be described with reference to the time chart of FIG. In FIG. 3, (a) shows the change in battery voltage, (b) shows the change in engine speed, (c) shows the change in the valve opening drive signal for the gaseous fuel injection valve 21, and (d) shows the change in the gaseous fuel injection valve 21. The transition of the supply gas pressure, (e) shows the transition of opening and closing of the tank main stop valve 44 and the shutoff valve 45, respectively.

In FIG. 3, when there is a start request (ON operation of the IG switch 26) from the driver, the tank main stop valve 44 and the shutoff valve 45 are switched to the open state (time t10). Subsequently, when the starter switch 27 is turned on by the driver, electric power is supplied from the battery 93 to the starter 25, and initial rotation is applied to the engine 10 (time t11). Thereafter, after the cylinder discrimination is completed, an injection command is output to the gaseous fuel injection valve 21 of each cylinder 24 in accordance with a predetermined combustion order (from time t12).

The case where the gas fuel injection valve 21 is not driven to open even if the supply gas pressure of the gas fuel injection valve 21 is in a high pressure state and the valve opening drive signal is output to the gas fuel injection valve 21 in duplicate with the starter drive. Think. In this case, combustion in the engine 10 is not started, and the engine speed does not rise from the cranking speed N1.

The starter switch 27 is temporarily turned off by the driver at time t13 after cranking has continued for a predetermined time, so that the drive of the starter 25 is stopped. In this embodiment, immediately after the starter switch 27 is turned off, power is supplied to the gaseous fuel injection valve 21 for a predetermined time as valve opening promotion control (t14 to t15). Here, the gas fuel injection valves 21 of all cylinders are energized continuously for a predetermined time. At this time, since the drive of the starter 25 is stopped, the battery voltage has sufficiently recovered, and thus the gaseous fuel injection valve 21 is opened by energization from time t14 to t15. In addition, as the valve is opened, fuel is injected (gas vented) from the gaseous fuel injection valve 21 so that the supply gas pressure is reduced to the set pressure Po or the vicinity thereof.

Thereafter, when the starter switch 27 is turned on again by the driver, the starter 25 is driven again (time t16). Further, after the cylinder discrimination is completed, combustion in the engine 10 is started. At this time, at least in the first fuel injection, fuel injection by the gaseous fuel injection valve 21 is prohibited, and only ignition by the ignition device 20a is performed.

Here, the time (t15 to t16) from when the valve opening promotion control is performed until the starter switch 27 is turned on again is usually as short as several seconds. Therefore, when the starter switch 27 is turned on again (t16), there is a high possibility that the gaseous fuel injected by the valve opening promotion control still remains in the intake port. In consideration of these points, in the present embodiment, at least the first combustion, the fuel injection by the gaseous fuel injection valve 21 is prohibited and only the ignition is performed. Specifically, even if the cylinder discrimination is completed at time t17 in FIG. 3, the subsequent first fuel injection is not performed, and the fuel injection is started in the cylinder of the next combustion order (time t18).

At time t18, the battery voltage is reduced due to the starter drive, but the gas fuel injection valve 21 is opened in accordance with the injection command because the injection hole is once opened by the valve opening promotion control. Gas fuel is injected. Further, combustion in the engine 10 is started by driving the ignition device 20a, and the engine 10 is started.

Next, the valve opening promotion control of the gaseous fuel injection valve 21 will be described with reference to the flowchart of FIG. This process is executed at predetermined intervals by the CPU 81 of the control unit 80.

In FIG. 4, in step S101, it is determined whether or not the IG switch 26 is turned on. If it is after the IG is turned on, the process proceeds to step S102, and the tank main stop valve 44 and the shutoff valve 45 are energized to switch to the valve open state. In a succeeding step S103, it is determined whether or not the starter 25 is being driven. Whether or not the starter is being driven is determined based on a detection signal of this sensor provided with a sensor for detecting the on / off switching of the starter switch 27.

If the starter 25 is being driven, an affirmative determination is made in step S103 and the process proceeds to step S104. In step S104, it is determined whether there is an execution history of valve opening promotion control. If there is no execution history, it will progress to step S105 and will command the fuel injection by the gaseous fuel injection valve 21 to be started. Here, immediately after the cylinder discrimination is completed, an injection pulse signal is output to each cylinder 24 in accordance with a predetermined combustion order. After that, in step S107, the starter drive time TB is counted as the elapsed time from the start of starter 25 drive (cranking start). Further, the battery voltage during cranking is acquired, and these pieces of information are stored in the RAM 83.

If combustion is not started by the injection command after IG-ON and the driver switches the starter switch 27 to OFF, a negative determination is made in step S103 and the process proceeds to step S108. In step S108, it is determined whether or not the engine has been started. Whether the engine 10 is before starting is determined, for example, based on whether the engine speed is lower than a predetermined starting determination speed N2 (N2> N1).

If the engine has not been started yet, the process proceeds to step S109, and it is determined whether or not the gaseous fuel injection valve 21 has not been driven to open even though power is supplied to the gaseous fuel injection valve 21 to start combustion in the engine 10. (Non-open valve detector). Here, it is determined whether or not the starter driving time TB stored in the RAM 83 is equal to or longer than a predetermined time. When the starter driving time TB is less than the predetermined time, this routine is finished as it is. Note that 0 is set to the starter drive time TB immediately after IG-ON. Therefore, a negative determination is made in step S109 during the period after IG-ON until the starter switch 27 is turned on.

When the starter driving time TB is equal to or longer than the predetermined time, the process proceeds to step S110, and it is determined whether or not there is an execution history of valve opening promotion control. If there is no execution history of the valve opening promotion control, the process proceeds to step S111, the supply gas pressure detected by the pressure sensor 46b is input, and it is determined whether or not the input supply gas pressure is equal to or higher than a predetermined pressure. (High pressure judgment part).

When the supply gas pressure is equal to or higher than the predetermined pressure, the process proceeds to step S113, and valve opening promotion control is executed (valve opening control unit). Here, electric power is continuously supplied to the electromagnetic drive unit of the gaseous fuel injection valve 21 for a predetermined time. On the other hand, when it is determined that the supply gas pressure is less than the predetermined pressure, the process proceeds to step S112, the battery voltage during the previous cranking is read, and it is determined whether or not the read battery voltage is equal to or lower than the predetermined value. When it is determined that the battery voltage during cranking is equal to or lower than the predetermined value, the process proceeds to step S113, and valve opening promotion control is executed.

After executing the valve opening promotion control, the process proceeds to step S114, and a history (execution history) indicating that the valve opening promotion control has been executed is stored in the RAM 83. In the subsequent step S115, the starter driving time TB is reset.

When the starter switch 27 is turned on again by the driver after that, the affirmative determination is made in step S103 and step S104, and the process proceeds to step S106. In step S106, in at least the first combustion after cylinder discrimination, only ignition is performed in a state where fuel injection is prohibited, and then fuel injection and ignition are performed. In this embodiment, only the first fuel injection during cranking is prohibited. Thereafter, the process of step S107 is executed.

Now, when the engine 10 is started, a negative determination is made in step S108, and the process proceeds to step S118. In step S118, the execution history of valve opening promotion control is deleted. Then, it progresses to step S115 and resets starter drive time TB.

Here, if the gaseous fuel supply unit 40 including the gaseous fuel injection valve 21 is normal, the gaseous fuel injection valve 21 cannot be opened due to a decrease in battery voltage during cranking or an increase in supply gas pressure. However, once the injection hole is opened by performing the valve opening promotion control, the subsequent opening operation of the gaseous fuel injection valve 21 is facilitated. Therefore, once the injection hole is opened by the valve opening promotion control, the gas fuel injection valve 21 operates normally even when the gas fuel injection valve 21 is energized during the cranking period at the next engine start. It should be. Nevertheless, if the engine 10 cannot be started at the next engine start, an abnormality has occurred in the fuel supply system (gaseous fuel supply unit 40), and the gas fuel injection valve 21 can be opened by the valve opening promotion control. It can be judged that there was not. In addition, as abnormality of the gaseous fuel supply part 40, the valve opening defect of the gaseous fuel injection valve 21, the valve opening defect of the tank main stop valve 44 or the shutoff valve 45 etc. are assumed, for example.

In view of these points, in the present embodiment, after the execution of the valve opening promotion control, when the engine 10 cannot be started despite the attempt to start the engine 10 by supplying power to the gaseous fuel injection valve 21. It is determined that an abnormality has occurred in the fuel supply system. Specifically, it is determined in step S108 of FIG. 4 that the engine has not been started, it is determined in step S109 that the gaseous fuel injection valve 21 has not been driven to open, and there is a history of execution of valve opening promotion control in step S110. If it is determined, the process proceeds to step S117 and the fact that the injection system abnormality has occurred is stored.

If the gas fuel injection valve 21 cannot be driven to open during cranking even though the supply gas pressure is lower than the predetermined pressure and the battery voltage during cranking is higher than the predetermined value, an injection system abnormality has occurred. It is assumed that it has occurred. Therefore, if a negative determination is made in step S112, it is determined that there is an abnormality in the injection system (S117), and the process proceeds to step S115.

According to the embodiment described above in detail, the following effects can be obtained.

In the period from when the engine start request is generated to when combustion in the engine 10 is actually started, power is supplied to the gaseous fuel injection valve 21 during the period when the drive of the starter 25 is stopped. According to such a configuration, electric power can be supplied to the gaseous fuel injection valve 21 in a state where the driving power required for opening the gaseous fuel injection valve 21 is sufficiently secured, and the gaseous fuel injection valve 21 is appropriately opened. be able to. Further, once the gaseous fuel injection valve 21 is opened, the subsequent operability is improved. As a result, gaseous fuel can be supplied to the engine 10 and engine startability can be ensured.

Specifically, when it is detected that the gas fuel injection valve 21 has not been opened despite the power supply to the gas fuel injection valve 21 in response to the engine start request, the starter drive is performed after the detection. The valve opening promotion control is performed during the stoppage period. If the driver operates the IG switch 26 and the starter switch 27 to give an engine start command but the engine 10 does not start, the driver temporarily turns off the starter switch 27 and then turns the starter switch 27 again. It is possible to turn on. In the present embodiment, focusing on the fact that the battery voltage is recovered by stopping the starter 25 during the period from the start to the start of the starter switch 27, the valve opening promotion control is performed during the same period. According to such a configuration, even when the gas fuel injection valve 21 does not open when the power is supplied to the gas fuel injection valve 21 at the same time as the drive timing of the starter 25, the drive stop period of the starter 25 is thereafter stopped. The gaseous fuel injection valve 21 can be opened by energizing the gaseous fuel injection valve 21 with the aim of. Further, once the valve can be opened, the adhesion of the seal portion of the injection hole can be reduced, and the gaseous fuel injection valve 21 can be easily opened at the next cranking.

When the engine 10 cannot be started under a situation where the supply gas pressure detected by the pressure sensor 46b is higher than a predetermined pressure, the valve opening promotion control is performed during the period when the starter drive is stopped thereafter. . When the supply gas pressure is in a high pressure state, the gaseous fuel injection valve 21 is difficult to open, and it is considered that the gaseous fuel injection valve 21 did not open during cranking due to this. In view of this point, by adopting the above-described configuration, it is possible to identify a factor that could not start the engine 10 and to take measures appropriate to the factor.

When the engine voltage could not be started under a situation where the battery voltage during cranking is lower than a predetermined value, the valve opening promotion control is performed during the period when the starter drive is stopped thereafter. When the battery voltage during cranking is in a low state, the gaseous fuel injection valve 21 is difficult to open, and it is assumed that the gaseous fuel injection valve 21 did not open during cranking due to this. Is done. In view of this point, by adopting the above-described configuration, it is possible to specify that the factor that could not start the engine 10 is the malfunction of the gaseous fuel injection valve 21, and it is possible to take measures suitable for the factor.

¡At the time of engine start immediately after the valve opening promotion control is performed, the fuel injection is prohibited at least in the first combustion. The time from when the valve opening promotion control is performed to when the starter switch 27 is turned on again is relatively short. Therefore, when the starter switch 27 is turned on again, the gaseous fuel injected by the valve opening promotion control is reduced. There is a high possibility that it is still in the intake port. By considering this point and adopting the above-described configuration, combustion can be performed with an optimum amount of fuel for combustion.

When it is detected that the gaseous fuel injection valve 21 has not been opened despite the fact that power is supplied to the gaseous fuel injection valve 21 at the time of engine start immediately after the valve opening promotion control is performed, the fuel injection system It was set as the structure judged to be abnormal. If the gaseous fuel supply unit 40 is normal, valve opening promotion control is performed even if the gaseous fuel injection valve 21 cannot be opened due to a decrease in the battery voltage during cranking or an increase in the supply gas pressure. Thus, the valve opening operation of the gaseous fuel injection valve 21 should be facilitated by opening the injection hole once. Nevertheless, if the engine 10 cannot be started at the next engine start, it can be determined that an abnormality has occurred in the fuel supply system and the gas fuel injection valve 21 could not be opened by the valve opening promotion control. By taking the above configuration into consideration, it is possible to identify an abnormality in the fuel supply system.
(Second Embodiment)
Next, the second embodiment will be described focusing on the differences from the first embodiment. In the first embodiment, valve opening promotion control is performed when it is detected that the gaseous fuel injection valve 21 has not been opened despite the fact that power is supplied to the gaseous fuel injection valve 21 in response to the engine start request. It was set as the structure to do. On the other hand, in the present embodiment, it is determined whether or not the gaseous fuel injection valve 21 is estimated not to open even if power is supplied to the gaseous fuel injection valve 21, and based on the determination result. The valve opening promotion control is performed before the starter 25 starts to be driven.

The configuration of the fuel injection system of the multi-cylinder engine in the present embodiment is basically the same as that in the first embodiment, but is different from the first embodiment in that the drive timing of the starter 25 can be arbitrarily controlled. Specifically, in the configuration of the power supply system in FIG. 2, the starter switch 27 is switched on / off in response to a control signal from the control unit 80 instead of being switched on / off in response to a driver operation. The starter 25 is driven when the starter switch 27 is turned on based on a control signal from the control unit 80, and applies an initial rotation to the engine 10. Note that the IG switch 26 of the present embodiment is, for example, a starter button for starting the engine 10 by performing starter driving and combustion control of the engine 10 in accordance with the driver's on operation.

Next, the valve opening promotion control of this embodiment will be described with reference to the time chart of FIG. 5, (a) to (e) are the same as those in FIG. 3, and (f) shows the transition of the on / off control of the starter switch 27.

In FIG. 5, when the IG switch (start button) 26 is turned on, the tank main stop valve 44 and the shutoff valve 45 are opened (time t20). At this time, even if power is supplied to the gaseous fuel injection valve 21, if it is estimated that the gaseous fuel injection valve 21 will not open, as a valve opening promotion control, the gaseous fuel injection valve 21 is given a predetermined time. The power is continuously supplied (t21 to t22). “Under the situation where it is estimated that the gaseous fuel injection valve 21 will not open” means that the battery voltage is less than a predetermined value when the supply gas pressure of the gaseous fuel injection valve 21 is equal to or higher than a predetermined pressure at the time of engine start request. And the case where the engine coolant temperature is equal to or lower than a predetermined temperature.

When the valve opening promotion control is completed, the starter 25 is driven (time t23), and the combustion control of the engine 10 is started after the cylinder discrimination is completed (time t24-). At this time, fuel injection is not performed in the first combustion after cylinder discrimination, only ignition by the ignition device 20a is performed, and fuel injection is started in the cylinder of the next combustion order (time t25). Then, as the engine 10 is started, the starter 25 is stopped.

FIG. 6 is a flowchart showing a processing procedure of valve opening promotion control of the present embodiment. This process is executed at predetermined intervals by the CPU 81 of the control unit 80. In addition, about the same process as FIG. 4 of the said 1st Embodiment, the step number of FIG. 4 is attached | subjected and the description is abbreviate | omitted.

In FIG. 6, in steps S301 and S302, the same processing as in steps S101 and S102 of FIG. 4 is executed. In a succeeding step S303, it is determined whether or not there is an execution history of the valve opening promotion control. If there is no execution history of valve-opening promotion control, the process proceeds to step S304, and it is determined whether or not it is in a state where it is estimated that the gaseous fuel injection valve 21 will not open (unopened estimation unit). Here, at least of the three conditions that the supply gas pressure of the gaseous fuel injection valve 21 is equal to or higher than a predetermined pressure, the battery voltage is equal to or lower than a predetermined value, and the engine coolant temperature is equal to or lower than a predetermined temperature. An affirmative determination is made when either is true.

If an affirmative determination is made in step S304, the process proceeds to step S305 to execute valve opening promotion control, and the execution history of valve opening promotion control is stored in step S306.

If it is determined in step S303 that there is an execution history of the valve opening promotion control, or if it is determined in step S304 that the gaseous fuel injection valve 21 is not in a situation where it is estimated that the valve will not open, the process proceeds to step S307. Then, the starter switch 27 is turned on to drive the starter 25. During driving of the starter 25, the driving time TB is counted and stored. In step S308, the fuel injection valve 21 and the ignition device 20a are driven so that the combustion of the engine 10 is started. When there is an execution history of valve opening promotion control, fuel injection in the first combustion during cranking is prohibited.

In subsequent step S309, it is determined whether or not the engine has been started. If it is after engine start, it will progress to step S310, will clear the execution history of valve opening promotion control, and will complete this routine. On the other hand, if it is before the engine is started, the process proceeds to step S311 and it is determined whether or not it is detected that the gaseous fuel injection valve 21 is not driven to open. Here, it is determined whether or not the starter driving time TB is equal to or longer than a predetermined time. If the starter drive time TB is equal to or longer than the predetermined time TB, the process proceeds to step S312 to store that an injection system abnormality has occurred, and this routine is terminated.

Even if power is supplied to the gaseous fuel injection valve 21, if it is determined that the gaseous fuel injection valve 21 is not expected to open, valve opening promotion control is performed before the starter 25 is driven. The configuration. If the supply gas pressure of the gaseous fuel injection valve 21 is already high, the battery voltage is low, or the engine is cold when the engine start request is generated, it overlaps with the drive timing of the starter 25. There is a concern that even if the driving power is supplied to the gaseous fuel injection valve 21, the gaseous fuel injection valve 21 cannot be opened. By taking the above configuration into consideration, it is possible to prevent a situation where the engine 10 cannot be started even if engine start control is performed.

(Other embodiments)
The present disclosure is not limited to the description of the above embodiment, and may be implemented as follows, for example.

In the first embodiment, when it is detected that the gaseous fuel injection valve 21 has not been driven to open when power is supplied to the gaseous fuel injection valve 21 at the same time as the starter 25 is driven, the next engine More specifically, the valve opening promotion control is performed immediately after the starter 25 is switched from the power supply state to the power cut-off state at the earliest possible timing within the period until the start request is generated. The timing for performing the valve opening promotion control is not limited to this. For example, the valve opening promotion control may be performed at a timing when a predetermined time has elapsed after the starter 25 is switched to the power cutoff state due to the engine 10 not being started.

In a system in which the drive timing of the starter 25 can be controlled arbitrarily, it was detected that the gaseous fuel injection valve 21 was not driven to open when power was supplied to the gaseous fuel injection valve 21 overlapping the drive timing of the starter 25. When the valve opening promotion control is performed later, the valve opening promotion control is performed immediately before the next starter drive. By doing so, the gaseous fuel injected by the valve opening promotion control can be surely introduced into the combustion chamber at the next starter driving, which is significant in terms of improving startability.

FIG. 7 is a time chart showing a specific mode when the valve opening promotion control is performed immediately before the starter driving. In the figure, (a) to (e) are the same as those in FIG. 3, and (f) shows the transition of driving / driving of the starter 25. In FIG. 7, it is assumed that the fuel injection and ignition are performed in accordance with the IG switch (start button) 26 being turned on, but the engine 10 cannot be started. In this case, when the drive of the starter 25 is temporarily stopped at the time t31, the valve opening promotion control is performed thereafter until the starter drive is performed again. Specifically, during the period in which the drive of the starter 25 is stopped, the gaseous fuel injection valve 21 is energized for a predetermined time at a timing t32 immediately before the starter 25 is started to drive the injection hole once (valve opening). Promotion control). Thereafter, the starter 25 is driven again at timing t33, and combustion control for starting the engine is started.

In the above-described embodiment, the gas fuel injection valve 21 is configured to perform control for promoting the opening of the gas fuel injection valve 21 by continuously energizing the gas fuel injection valve 21 for a predetermined time, but the mode of energization is not limited thereto. For example, as shown in FIG. 8, it is good also as a structure which implements the control which accelerates | stimulates valve opening by operating the gaseous fuel injection valve 21 by the intermittent energization which repeats energization / non-energization of the gaseous fuel injection valve 21.

It is good also as a structure which changes the electricity supply aspect in valve-opening promotion control according to the factor estimated that the gaseous fuel injection valve 21 was not valve-opening driven, or not valve-opening driven. As an example, in the first embodiment, when it is detected that the supply gas pressure is equal to or higher than a predetermined value, the valve opening promotion control is performed by continuously supplying power to the gaseous fuel injection valve 21. carry out. On the other hand, when it is detected that the supply gas pressure is less than the predetermined value, valve opening promotion control is performed by intermittently supplying power to the gaseous fuel injection valve 21. In the former case, it is considered that the gaseous fuel injection valve 21 was not driven to open due to the supply gas pressure being in a high pressure state. In such a case, the gaseous fuel injection valve 21 is continuously energized to quickly reduce the supply gas pressure (see FIG. 3). On the other hand, if the supply gas pressure is not so high but the gaseous fuel injection valve 21 is not driven to open, it is considered that the sticking of the seal portion of the injection hole is strong. In such a case, the gaseous fuel injection valve 21 is intermittently energized to peel off the sticking of the seal portion (see FIG. 8).

FIG. 9 is a flowchart showing a processing procedure for valve opening promotion control according to the present embodiment. In FIG. 9, basically the same processing as in FIG. 4 is executed, but the processing after it is determined in step S111 that the supply gas pressure is lower than the predetermined pressure is different. Therefore, FIG. 9 mainly shows processing different from that in FIG. In the description of FIG. 9, the same processes as those of FIG. 4 are denoted by the step numbers of FIG.

In FIG. 9, the same processing as in FIG. 4 is executed in steps S108 to S111, and it is determined whether or not the supply gas pressure is equal to or higher than a predetermined pressure in step S111. If the supply gas pressure is equal to or higher than the predetermined pressure, the process proceeds to step S113, and the gaseous fuel injection valve 21 is energized continuously for a predetermined time. On the other hand, if the supply gas pressure is less than the predetermined pressure, the process proceeds to step S112, and it is determined whether or not the battery voltage during cranking is equal to or lower than a predetermined value. If a negative determination is made, the process proceeds to step S117, and it is determined that there is an injection system abnormality. On the other hand, when an affirmative determination is made in step S112, the process proceeds to step S120, and the gas fuel injection valve 21 is repeatedly turned on / off with a pulse having a predetermined period.

In the valve opening promotion control of the first embodiment, power is supplied to the gaseous fuel injection valves 21 of all cylinders, but power may be supplied to some cylinders.

Based on the supply gas pressure of the gas fuel injection valve 21, a cylinder specifying unit is provided for specifying the gas fuel injection valve 21 of the cylinder that has not been opened when power is supplied redundantly when the starter 25 is driven. The gas fuel injection valve 21 is configured to supply power to the gas fuel injection valve 21 during a period in which the starter drive is stopped. According to such a configuration, it is not necessary to energize the cylinders that do not need to be energized to promote valve opening, and wasteful power consumption can be suppressed as much as possible.

A specific mode in which energization of the valve opening promotion control is performed on the gas fuel injection valve 21 of the specific cylinder will be described with reference to the time chart of FIG. In this configuration, the amount of change (amount of decrease) in the supply gas pressure with respect to the valve opening drive signal is monitored during the period t41 to t42 during which the cranking of the engine 10 is being performed. If the amount of decrease in the supply gas pressure is equal to or greater than a predetermined value, it is determined that the gaseous fuel injection valve 21 is appropriately driven to open in the cylinder for which the valve opening drive signal is to be output. On the other hand, if the amount of decrease in the supply gas pressure is less than the predetermined value, it is determined that the gaseous fuel injection valve 21 has not been driven to open in the cylinder for which the valve opening drive signal is to be output. For example, in FIG. 10, the combustion order is set to the first cylinder (# 1) → the second cylinder (# 2) → the third cylinder (# 3), and the supply gas pressure decreases in the first cylinder and the third cylinder. This shows a case where is not detected. In this case, power is supplied to the gaseous fuel injection valves 21 of the first cylinder and the third cylinder for a predetermined time after the time t42 when the starter switch 27 is once switched off by the driver.

In the valve opening promotion control of the first embodiment, power is supplied to the gaseous fuel injection valve 21 for a predetermined time, but the power supply time for the valve opening promotion control is variably set. Also good. For example, in the case where the valve opening promotion control is performed when it is determined that the supply gas pressure is higher than a predetermined high pressure determination value, as shown in FIG. Electric power is supplied to the gaseous fuel injection valve 21 until it is determined that the pressure is lower than a predetermined low pressure determination value (for example, a set pressure Po or a value in the vicinity thereof), and the supply gas pressure is a predetermined low pressure determination value. The power supply is stopped at time t51 when it is determined that the power supply has decreased. By adopting such a configuration, even when the gas fuel injection valve 21 is driven in an overlapping manner with the drive of the starter 25, the supply gas pressure is sufficiently reduced to the extent that the gas fuel injection valve 21 can be opened. Can do.

In the first embodiment, at the time of engine start immediately after the valve opening promotion control is performed, at least the fuel injection in the first combustion is prohibited. However, the fuel injection amount in the first combustion is corrected to decrease. Also good.

An abnormality in the fuel injection system when it is detected that the gaseous fuel injection valve 21 does not open even when power is supplied to the gaseous fuel injection valve 21 when the engine is started after the valve opening promotion control is performed. It is good also as a structure which determines that the injection system abnormality has arisen when the drive frequency of the starter 25 (number of times of execution of valve opening promotion control) exceeds a predetermined frequency.

In the first embodiment, by counting the starter drive time TB, the gas fuel injection valve 21 was not driven to open when power was supplied to the gas fuel injection valve 21 in duplicate with the drive timing of the starter 25. However, the present invention is not limited to the method based on the starter driving time TB. For example, the engine rotational speed after a predetermined time has elapsed since the starter drive may be detected, and the detected engine rotational speed may be detected based on being lower than a predetermined value.

In the above embodiment, the case where the present invention is applied to a three-cylinder engine has been described. However, the number of cylinders is merely an example, and the present invention may be applied to a multi-cylinder engine such as a four-cylinder engine, a six-cylinder engine, or an eight-cylinder engine.

In the above embodiment, the gaseous fuel injection valve 21 is directly attached to the branch pipe portion 13 a. However, the injection pipe is connected to the tip of the gaseous fuel injection valve 21, and this injection pipe branches from the intake manifold 13. It is good also as a structure attached to the pipe part 13a.

In the above embodiment, the case of applying to a gas-dedicated on-vehicle engine that uses only gaseous fuel as engine combustion fuel has been described. However, a bi-fuel type that uses gaseous fuel and liquid fuel as engine combustion fuel is used. You may apply to a vehicle-mounted engine.

In the above embodiment, a plurality of gaseous fuel injection valves 21 are provided for each cylinder of the multi-cylinder engine. However, the gaseous fuel injection valves 21 are provided in a common portion of the plurality of cylinders, and the intake system 11 is connected to the collective portion. The gaseous fuel may be injected.

In the above embodiment, the gaseous fuel is CNG fuel, but other gaseous fuels may be used. For example, a configuration using a fuel whose main component is methane, ethane, propane, butane, hydrogen, dimethyl ether, or the like may be used.

Claims

A gas fuel injection valve (21) that injects gaseous fuel as an electric load driven by power supply from the power supply unit (93), and a starter (25) that applies initial rotation to the engine output shaft when a start request occurs. And an internal combustion engine (10) comprising:
A combustion control unit configured to perform combustion in the internal combustion engine by supplying electric power from the power source unit to the gaseous fuel injection valve when the start request occurs;
The starter is driven within a predetermined period from when the start request is generated to when combustion in the internal combustion engine is actually started with the supply of power to the gaseous fuel injection valve by the combustion control unit. A valve opening control unit for performing valve opening promotion control for supplying electric power to the gaseous fuel injection valve during a period of stoppage;
A fuel injection control device for an internal combustion engine, comprising:
A high pressure determination unit that determines whether or not a fuel supply pressure that is a pressure of fuel supplied to the gaseous fuel injection valve is higher than a predetermined high pressure determination value;
The valve opening control unit promotes the valve opening during a period in which the driving of the starter is stopped when the high pressure determination unit determines that the fuel supply pressure is higher than the predetermined high pressure determination value. The fuel injection control device for an internal combustion engine according to claim 1, wherein the control is performed.
A low pressure determination unit that determines whether or not the fuel supply pressure is lower than a predetermined low pressure determination value;
The valve opening control unit supplies power to the gaseous fuel injection valve in the valve opening promotion control until the low pressure determination unit determines that the fuel supply pressure has decreased below the predetermined low pressure determination value. The fuel injection control device for an internal combustion engine according to claim 2.
A voltage detection unit for detecting an output voltage of the power supply unit;
The valve opening control unit performs the valve opening promotion control during a period in which the driving of the starter is stopped when the output voltage detected by the voltage detection unit is lower than a predetermined value. 4. The fuel injection control device for an internal combustion engine according to claim 3.
A non-opening detection unit that detects that the gaseous fuel injection valve has not been opened when power is supplied to the gaseous fuel injection valve by the combustion control unit during a period when the starter is being driven; ,
When the non-opening detection unit detects that the gaseous fuel injection valve has not opened, the valve opening control unit opens the valve during a period when the starter is not driven after the detection. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the valve promotion control is performed.
The internal combustion engine is provided with the gaseous fuel injection valve for each cylinder,
Based on the fuel supply pressure that is the pressure of the fuel supplied to the gaseous fuel injection valve, the gaseous fuel injection valve did not open even though power was supplied to the gaseous fuel injection valve by the combustion controller. It has a cylinder identification part that identifies the cylinder,
The said valve opening control part supplies electric power to the said gaseous fuel injection valve in the period when the drive of the said starter has stopped with respect to the said gaseous fuel injection valve of the cylinder specified by the said cylinder specific | specification part. A fuel injection control device for an internal combustion engine according to claim 1.
The starter is configured to switch between driving and stopping when the power supply state and the power cut-off state are switched by the operation of the driver.
The valve-opening control unit performs the valve-opening promotion control immediately after the start-up request is switched from the power supply state to the power cut-off state by a driver operation after the start-up request is generated. A fuel injection control device for an internal combustion engine as described.
The timing of power supply from the power supply unit to the starter can be arbitrarily controlled,
The fuel injection control device for an internal combustion engine according to claim 5 or 6, wherein the valve opening control unit performs the valve opening promotion control immediately before switching the starting device from a power cutoff state to a power supply state.
Even if power is supplied to the gaseous fuel injection valve by the combustion control unit, an unopened valve estimation unit that determines whether or not the gaseous fuel injection valve is estimated to not open is provided.
The valve opening control unit promotes the valve opening before driving the starting device when it is determined by the non-open valve estimating unit that the gaseous fuel injection valve is estimated not to open. The fuel injection control device for an internal combustion engine according to claim 1, wherein the control is performed.
A unit for prohibiting at least fuel injection in the first combustion or correcting the fuel injection amount in the first combustion to be reduced when starting the internal combustion engine after performing the valve opening promotion control. The fuel injection control device for an internal combustion engine according to any one of the above.
When starting the internal combustion engine after performing the valve opening promotion control, if the gaseous fuel injection valve does not open even if power is supplied to the gaseous fuel injection valve, the fuel injection system is abnormal. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 10, further comprising an abnormality determination unit for determining.